Imperative to keep blade cool BEFORE heat treatment?

[Don Hanson III]

From what I gather....if grinding post heat treat....you don't want the blade to reach tempering temperature. I would say that is right at 300F. Do all you can to keep the blade from even warming up AT ALL....yes....that is the best. But.....the fact is after heat treat....for carbon steel......staying below 300 or technically your final tempering temperature is all that is required. Tempering colors will show if you get that hot....and sometimes you're OK even if say the tip reaches that light straw color...because the depth of "damage" may only have been skin deep, or it may have gone all the way through.



Pre heat treat. I would think that you could get the blade all the way up to red hot heat if you wanted to while grinding. Of course....I wouldn't say taking it to a yellow heat is good while grinding. I didn't think anyone would even attempt that. But after taking a blade that hot while grinding....it might be a grand idea to normalize and then stress relieve afterwards. "As hot as you want" was incorrect on my part, I was assuming you couldn't hold onto it for any length of time at a yellow heat, and it would probably plastic deform on you as you press against the platen. Just speculating on what would happen if one attempted such.

Does that sound right...or what am I missing?

Yes, but you could go to 400 or so after HTing with most steels.

 

[samuraistuart]

Thanks Don. I was trying to play it safe with the 300F number.

 

[mete]

First it's metallurgical ! Next it's crystalline NOT molecular. Heating from grinding [before HT] is not bad as long as it's then sub-critical annealed [1200 F for two hours] , or normalized .

It's VERY easy to damage the blade after HT when grinding. Best to grind most of the way before HT then carefully under flowing coolant or by hand with coolant.This has been proven under careful tests !!!